Der Beitrag schlägt ein Klassifikationssystem für keramische und keramikähnliche Restaurationsmaterialien unter Berücksichtigung einer neuen Materialklasse vor. Die neue Klassifikation ordnet keramische Restaurationsmaterialien in drei Familien: Glasmatrix-, polykristalline und Kunststoffmatrix-Keramiken. Außerdem werden die vom Hersteller angegebenen klinischen Indikationen der verschiedenen Materialien genannt, die Verarbeitungstechniken werden überblicksartig aufgeführt und es wird angegeben, ob die Materialien als Gerüstwerkstoffe oder für monolithische Lösungen verwendet werden. Keywords: Dentalkeramik, Klassifikation, Glaskeramik, polykristalline Keramik, Kunststoffmatrixkeramik, Feldspatkeramik, Lithiumdisilikat, Zirkonoxid, Aluminiumoxid, Kunststoffnanokeramik, Hybridkeramik

Purpose: To investigate the influence of atmospheric pressure plasma (APP) treatment on the microtensile dentin bond strength of two etch-and-rinse adhesive systems, after one week and one year of water storage, and additionally to observe the micromorphology of resin/dentin interfaces under scanning electronic microscopy (SEM). Materials and Methods: The occlusal enamel was removed from third human molars to expose a flat dentin surface. The teeth were then randomly divided into six groups (n = 7), according to two adhesives (Optibond FL and XP-Bond) and three APP treatments (untreated dentin [control], APP application before or after acid etching). After performing the composite resin buildup on bonded dentin, the teeth were sectioned perpendicularly to the bonded interface to obtain beam-shaped specimens (cross-sectional area of ~0.9 mm2). The specimens were tested in tension until failure after one week and one year of water storage (1.0 mm/min rate). Bond strength data were analyzed by three-way ANOVA and Tukey's post-hoc test (α = 0.05%). Bonded beam specimens from each tooth were also prepared for interfacial SEM investigation. Results: At one week, APP treatment applied after acid etching increased the dentin bond strength for XP Bond, while no effect was observed for Optibond FL. After one year, the bond strength of XP Bond decreased in groups where APP was applied after etching. The evaluation time did not influence the bond strength for Optibond FL. Conclusion: One-year evaluation did not show any sign of degradation of interfacial structures in any group. Application of APP to etched dentin combined with a two-step etch-and-rinse adhesive significantly increased bond strength at one week, but the effect was not stable after one year and was adhesive dependent. Keywords: plasma, microtensile, dentin adhesion

Purpose: To determine the influence of atmospheric pressure plasma (APP) treatment on the microtensile dentin bond strength of two self-etching adhesive systems after one year of water storage as well as observe the contact angle changes of dentin treated with plasma and the micromorphology of resin/dentin interfaces using SEM. Materials and Methods: For contact angle measurements, 6 human molars were sectioned to remove the occlusal enamel surface, embedded in PMMA resin, and ground to expose a flat dentin surface. Teeth were divided into two groups: 1) argon APP treatment for 30 s, and 2) blown air (control). For the microtensile test, 28 human third molars were used and prepared similarly to contact angle measurements. Teeth were randomly divided into 4 groups (n = 7) according to two self-etching adhesives and APP treatment (with/without). After making the composite resin buildup, teeth were sectioned perpendicular to the bonded interface to obtain beam specimens. The specimens were tested after 24 h and one year of water storage until failure. Bond strength data were analyzed by three-way ANOVA and Tukey's post-hoc test (α = 0.05%). Three beam specimens per group that were not used in the bond strength test were prepared for interfacial SEM analysis. Results: APP application decreased the contact angle, but increased the bond strength only for one adhesive tested. SEM evaluation found signs of degradation within interfacial structures following 1-year aging in water. APP increased the dentin surface energy, but the effects of APP and 1-year water storage on dentin bond strength were product dependent. Conclusion: APP increased the dentin surface energy. It also increased the bond strength for Scotchbond Universal, but storage for one year negated the positive effect of APP treatment. Keywords: plasma, microtensile, dentin adhesion

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

Fracture strength and accelerated fatigue reliability of two zirconia abutment systems were tested. Thirty-six implants with a Morse taper (MT; n = 18) or cone (C; n = 18) design were restored with metallic crowns. Loads were applied as single load to failure (SLF) or mouth-motion cycles using a step-stress accelerated life testing (SALT) method. SLF mean values were 690 ± 430 N and 209 ± 25 for MT and C groups, respectively. In terms of the SALT results, 8 specimens survived (50,000 cycles) and 7 failed (maximum load 400 N) in the MT group; whereas for the C group all abutments failed before the maximum number of cycles. Failure mode was fracture of the Y-TZP abutments for both groups. Higher reliability for a mission of 50,000 cycles at 175 N for MT versus C designs was determined, and significant differences in fracture modes were observed.

Purpose: Microgaps at the implant-abutment interface allow for microbial colonization, which can lead to peri-implant tissue inflammation. This study sought to determine the marginal accuracy of three different implant-zirconium oxide (zirconia) abutment configurations and one implant-titanium abutment configuration. Materials and Methods: Three combinations of implants with custom-made zirconia abutments were analyzed (n = 5/group): NobelProcera abutments/titanium inserts on Replace Select Tapered TiUnite implants (Nobel Biocare) (NP); Encode abutments/NanoTite Tapered Certain implants (Biomet 3i) (B3i); Astra Tech Dental Atlantis abutments/Biomet 3i NanoTite Tapered Certain implants (At). Five custom-made Encode titanium abutments/NanoTite Tapered Certain implants (Ti) were used as a control group. All abutments were fabricated with computer-aided design/computer-assisted manufacture. One-hundred twenty vertical gap measurements were made per sample using scanning electron microscopy (15 scans × 4 aspects of each specimen [buccal, mesial, palatal, distal] × 2 measurements). Analysis of variance was used to compare the marginal fit values among the four groups, the specimens within each group, and the four aspects of each specimen. Results: Mean (± standard deviation) gap values were 8.4 ± 5.6 µm (NP), 5.7 ± 1.9 µm (B3i), 11.8 ± 2.6 µm (At), and 1.6 ± 0.5 µm (Ti). A significant difference was found between B3i and At. No difference resulted between NP with the other two groups. Gap values were significantly smaller for Ti relative to all zirconia systems. For each ceramic abutment configuration, the fit was significantly different among the five specimens. For 12 of the 15 ceramic abutment specimens, gap values sorted by aspect were significantly different. Conclusions: The implant-titanium abutment connection showed significantly better fit than all implant-zirconia abutment configurations, which demonstrated mean gaps that were approximately three to seven times larger than those in the titanium abutment system. Keywords: custom abutment, dental implant, marginal accuracy, titanium, zirconium oxide

Purpose: The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns. Materials and Methods: A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. Results: Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N. Conclusion: Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures.

The fracture strength and accelerated fatigue reliability of metal and zirconia abutment systems were tested. Implants with either titanium (Ti, n = 9) or zirconia abutments (Zr, n = 18) were restored with metal crowns. Loads were applied as either a monotonic load to failure or mouth-motion cycles using a step-stress accelerated life testing method. At failure, monotonic loads were 1,475 ± 625 N for Ti and 690 ± 430 N for Zr. In step-stress testing, the Ti group was truncated at 70,000 cycles and a 900-N load with no fractures. In the Zr group, eight specimens survived and seven failed, with a maximum load of 400 N. Strength and reliability were significantly higher for the Ti abutments compared to the Zr.

Objective: To test the effect of different veneering techniques on failure modes and the reliability of veneered yttrium oxide partially stabilized tetragonal zirconia polycrystal (Y-TZP) in a veneer/core/composite trilayer configuration subjected to 30- degree off-axis mouth-motion step-stress fatigue. Methods: CAD/CAM Y-TZP zirconia plates were veneered using a lost-wax press technique (IPS e.max ZirPress, Ivoclar Vivadent, test group press, n = 24) and a hand build-up technique (IPS e.max Ceram, Ivoclar Vivadent, control group layer, n = 24) (12x12x0.7 mm). After adhesive bonding (Alloy Primer and Panavia 21, Kuraray) to resin-based composite blocks (12x12x4 mm, Z-100), samples were stored in water for 7 days prior to fatigue testing. Trilayer specimens were mouthmotion step-stressed using three profiles (EL-3300, Bose/Enduratec), with a spherical tungsten carbide indenter (r = 3.18 mm) until cracks reached the veneercore interface. All flat-layer specimens were angled 30 degrees with respect to the loading axis, simulating posterior tooth cusp inclination. Step-stress profiles were determined from single-cycle load-to-failure tests (n = 3). Results: Single-cycle load-to-failure tests yielded 825 N for the test group press and 803 N for the control group layer. Irrespective of the applied veneering technique, Y-TZP trilayers failed from surface deep cone cracks reaching the veneercore interface. Radial fractures of the YTZP cores were not present. Weibull stress level probability curves were calculated (AltaPro, ReliaSoft). Similar reliabilities (0.54 test group press, 0.51 control group layer) were determined at 100,000 cycles and a 200 N load. Conclusion: After occlusion-like loading the step-stress fatigue reliability of pressed and layered veneering ceramics over Y-TZP cores was comparable. Fracture was limited to surface damage in the veneer layer. Failure modes were identical for both veneering techniques. Bulk fracture of the YTZP core material was not observed.

Ziel: Auswertung des Einflusses verschiedener Verblendtechniken auf das Versagensverhalten und die Dauerbelastbarkeit von verblendetem Yttrium-teilstabilisiertem tetragonalem Zirkonoxidpolykristall (Y-TZP) in einem Verblendung-Gerüst-Komposit- Dreischichtsystem, das unter 30-Grad- Abwinkelung einem Kausimulation-Stufen- Belastungstest unterworfen wurde. Methoden: CAD/CAM-Y-TZP-Zirkonoxidplättchen wurden mit einer Wachsausschmelz- Presstechnik (IPS e.max ZirPress, Ivoclar Vivadent), Testgruppe [Presstechnik], n = 24) und einer Schichttechnik (IPS e.max Ceram, Ivoclar Vivadent, Kontrollgruppe [Schichttechnik], n = 24) (12 x 12 x 0,7mm) verblendet. Nach der adhäsiven Befestigung (Alloy Primer und Panavia 21, Kuraray) auf Kompositblöcke (12 x 12 x 4 mm, Z-100) wurden die Prüfkörper vor den Ermüdungstests sieben Tage in Wasser gelagert. Die dreischichtigen Prüfkörper wurden in einem Kausimulation-Stufen-Belastungstest mit einem kugelförmigen Wolframkarbid- Belastungskörper (R = 3,18mm) belastet und drei unterschiedlichen Profilen (EL-3300, Bose/Enduratec) unterzogen, bis die Risse die Verbundzone zwischen Verblend- und Gerüstkeramik erreichten. Alle Prüfkörper wurden im Winkel von 30 Grad in Relation zur Belastungsachse angeordnet, um die Höckerneigung im Seitenzahnbereich zu simulieren. Die stufenförmigen Belastungsprofile wurden anhand der initialen Bruchfestigkeit ermittelt (n = 3). Ergebnisse: Der initiale Bruchfestigkeitstest ergab für die Testgruppe (Presstechnik) 825 N, für die Kontrollgruppe (Schichttechnik) 803 N. Bei beiden Verblendtechniken versagten die dreischichtigen Y-TZP-Prüfkörper aufgrund von der Oberfläche ausgehenden konusförmigen Rissen, die die Verblendung-Gerüst-Verbundzone erreichten. Es lagen keine Radialfrakturen der Y-TZP-Gerüste vor. Belastungsabhängige Weibull-Wahrscheinlichkeitskurven wurden berechnet (AltaPro, ReliaSoft). Bei 100000 Zyklen und einer Belastung von 200 N wurden ähnliche Werte für die Dauerbelastbarkeit ermittelt (Testgruppe 0,54, Kontrollgruppe 0,51). Zusammenfassung: Nach kauähnlicher Belastung war die Dauerbelastbarkeit bei stufenförmiger Materialermüdung bei der gepressten und der geschichteten Verblendkeramik auf Y-TZP-Gerüsten vergleichbar. Frakturen waren auf oberflächliche Schäden in der Verblendschicht begrenzt. Das Versagensverhalten war bei beiden Verblendtechniken identisch. Frakturen des Y-TZP-Gerüstmaterials wurden nicht beobachtet.